The obituaries for Flash were written long ago. But don’t tell that to the digital ad industry.

Last fall, Google announced it would stop accepting Flash video ads within its DoubleClick Digital Marketing ad platform by April 2017, with plans to stop running Flash ads completely through DDM by July. This is a big deadline for publishers with DDM responsible for a significant chunk of digital video advertising. Google’s announcement also came around the same time the Interactive Advertising Bureau set a July 2017 deadline for the complete migration from Flash video ads to HTML5.

Unfortunately, many marketers and ad tech vendors have not heard the call. Multiple publishers, speaking anonymously with Digiday due to existing relationships with advertising and technology partners, say that most advertisers and ad tech vendors are not fully prepared for the cutoff date, potentially leaving publishers to pick up the scraps and suffer losses in revenue.

For three different publishers, Flash ads still fill a majority of their on-site video inventory. One top news publisher said anywhere from 50 to 55 percent of its video ad impressions today are happening with ads built on Flash. “I was hopeful, given that we are a month away from Google’s deadline, that the numbers [for HTML5 video ad impressions] would be higher,” said a programmatic sales exec at this news publisher.

With Google’s plans to stop allowing Flash video ads to turn through DoubleClick Campaign Manager, DoubleClick Bid Manager, DoubleClick Bid Exchange and DoubleClick for Publishers and AdWords, that’s a significant chunk of revenue that publishers will lose. It’s an even bigger issue when considering how much Google Chrome accounts for web traffic.

“If the [full migration from Flash to HTML5] were to happen today, we would lose about 60 percent of our video revenue,” said a sales operations exec at another publisher.

Publishing sources point to agencies and ad tech vendors, who they claim are not incentivized enough — or aren’t aware enough — to stop delivering Flash video ads.

“A lot of the SSPs that are out there are not putting a hard line in the stand and saying, ‘We’re not going to serve Flash anymore,’” said the publishing sales operation exec. “Because of that, buyers are not incentivized to make the switch. Only if you buy through DDM are you going to be impacted.”

As evidence, this exec pointed to the drop-off their company saw after it started migrating to an HTML5-first video player at the beginning of the year. Immediately after introducing an HTML5 video player alongside the Flash video player it already had, fill rates fell by 40 to 50 percent.

“We’re reaching out to our network partners about this, and what we’ve found is that they’re not prepared,” said the sales exec at the news publisher. “For the most part, they’re working with creative coming from [agency] clients, which itself is coming from creative agencies, which created the ad months ago.”

One gaming publisher, which fully adopted HTML5 last fall, estimated a 20 percent drop-off in demand at the beginning of the year due to “one major DSP that did not have its act together.”

Agencies are not immune from blame, either. A publishing sales exec said that when the topic of HTML5 is brought up with clients, most act as if they’re not worried because the campaign will end before the Google and IAB deadlines. “If the campaign ends on July 1 and it’s successful, but the client isn’t ready to capitalize on the back end, there’s nothing we can do,” said this exec. “I can show you the report that we captured 90 percent of the audience you’re looking for, and the audience is available for the following month, but we can’t do anything because you won’t be ready with HTML5 creative.”

Publishing sources agree the shift toward HTML5 has been gradual as more agencies and vendors make the adoption. But with Google’s July deadline fast approaching, it will be publishers that get squeezed.

Publishers are already selling HTML5 video inventory at cheaper rates. One publisher said it’s charging 20 to 25 percent less CPMs for HTML5 video inventory just to be able to hit a minimum 90 percent fill rate.

“We’ve had days where more than 60 to 70 percent of our video inventory is HTML5, so we have the capabilities to fill it currently,” said the sales exec at the news publisher. “But I don’t know if that’s just for a couple of days per week, or if a week’s worth of inventory is even possible.”

Publishers say the platforms need to play a bigger role in getting agencies and vendors to adopt HTML5.

“The platforms are the pipes that connect both ends,” said the publishing sales operations exec. “If we’re all responding to them, they should do more since they’ve got the connections across the board.”

Others argued that it’s going to take more collaboration between publishers and vendors. “We’ve made the shift,” said a sales exec at the gaming publisher. “The technology companies need to get their act together.”